1. Field of the Invention
The present disclosure relates to a position pointer (stylus) having a shape of a pen and a signal processing circuit which capacitively detects the position pointer on a sensor. The present disclosure relates also to a signal supply controlling method for a position pointer and a signal processing method for capacitively detecting the position pointer on a sensor.
2. Description of the Related Art
A position detection apparatus such as a touch panel has come to be used widely, and various disclosures have been made for a position detection apparatus. Further, attention is paid to a position pointer called an active capacitive pen as a pointer used together with a position detection apparatus of a capacitance type. A type of an active capacitive pen is known which includes a driving power supply and an oscillator driven by the driving power supply, both provided in a housing, and in which an oscillation signal of the oscillator is outputted to a position detection apparatus. Also, another type of an active capacitive pen is known which receives a signal from a position detection apparatus and amplifies and outputs the signal to the position detection apparatus. A position detection apparatus receives a signal outputted from any of the position pointers of the types described and includes a sensor having first conductors of a first direction and second conductors of a second direction. The position detection apparatus detects a position pointed to by an active capacitive pen by receiving, at the first conductors of the first direction and the second conductors of the second direction of the sensor thereof, signals from the active capacitive pen through capacitive coupling (interaction with the capacitive pen).
For an active capacitive pen of the type described, it is demanded to input angle information such as an inclination angle of a position pointer as data in addiction to a coordinate value input.
In order to satisfy the demand, a technology which makes it possible to detect an inclination angle or the like of a position pointer on a sensor face of a position detection apparatus is proposed, for example, in Japanese Patent Laid-open No. 2014-35631 or U.S. Pat. No. 8,638,320 B2 (hereinafter, referred to as Patent Document 1 and Patent Document 2, respectively).
In Patent Document 1, in order to detect an inclination angle of a position pointer, a first electrode and a second electrode are provided on a core member, and an electrode from which an alternating current (AC) signal is to be outputted out is selected alternately from the first and second electrodes. Also, three electrodes are provided at an end portion on one side of a housing in such a manner as to surround a core member projecting from an opening of the housing, and an AC signal is supplied to one of the electrodes selected based on a pattern determined in advance.
Further, the position detection apparatus calculates an inclination angle or the like of the position pointer with respect to the sensor face from a plurality of coordinate positions or signal strengths on the sensor face which receives an AC signal from the position pointer. The coordinate positions are determined in accordance with pattern information received from the position pointer.
Meanwhile, in Patent Document 2, signals are supplied to tip electrodes (414 and 714) and an electrode (ring electrode 416) or electrodes (segment electrodes 716-A to 716-C) surrounding the tip electrode. Then, an inclination angle or the like of a position pointer (stylus) is detected at a touch panel from a reception pattern of a signal from the tip electrode and a reception pattern of a signal or signals from the surrounding electrode or electrodes.
Incidentally, an active capacitive pen of the type described is demanded to have a high performance. Particularly, it is demanded not only to detect angle information such as an inclination angle on a sensor face but also to detect an active capacitive pen also at a distance (height) spaced from the sensor face, namely, to assure a hovering distance (height) as great as possible. Also there is a demand to elongate the driving time period of an active capacitive pen by minimizing the power consumption.
In such a position detection apparatus of the capacitance type as is disclosed in Patent Documents 1 and 2, although an active capacitive pen is used, the position detection apparatus can merely detect the angle direction such as an inclination angle of the position pointer. However, both of the documents are silent of hovering and hence are silent of simultaneous improvement in hovering performance.
Meanwhile, an existing active capacitive pen outputs a same signal and uses a same outputting method irrespective of whether it is positioned in a spaced relationship from the sensor face of the position detection apparatus or positioned in the proximity of the sensor face. Besides, the existing active capacitive pen performs neither detection of angle information such as an inclination angle on the sensor face nor signal control which takes power consumption of the active capacitive pen into consideration.